since an Debian 9 update some weeks ago, I have the problem, that my Desktop (XServer + FVWM) is unexpected blanking.I have always to use <Ctrl><Alt><F1> and then <ALT><ARROW_LEFT> to get my Desktop back only that it start blanking again in non regular intervals...

I am using already

xset -dpms s off s blank

since quiet a while on my ThinkPad T400 and had NEVER a problem for years, but it seems, Debian has introduced a new bug in an update.

Anyone here which has the same problem?

Note: My T400 has multiboot and Debian 7+8 (I use the Laptop for Software Development) are working perfectly without any problems. Also I can install Debian 9.2 (from DVD) and the error is gone.

I have changed nothing since years.First I was thinking, that the Display/Controller of my ThinkPad T400 is broken, but since I can switch to the Console and back to FVWM Desktop, a mechanical or electrical failur is excluded. Also my Debian 7 and Debian 8 installations plus Debian 9.2 from DVD is working.